2c:null 2d:["$","title",null,{"children":"Printable Calendar Constraint Solver | Mateo Pedersen | Observable"}] 32:T521,# Printable Calendar Constraint Solver A printable calendar is a finite geometry allocation problem: fixed paper dimensions must hold a title, weekday labels, a date grid, and optional notes while preserving enough room to write. This tool varies paper, orientation, margin, month, week origin, and row policy, then reports the dimensions in millimeters. The model treats measurements as physical units. The preview is normalized to the screen and is not a printer scale guarantee. Cell area is a geometric proxy for writing room, not a usability claim. ## Solver Adjust the constraints below. The live preview, invalid-state checks, and comparison set update together. The Pareto view ranks feasible margin/notes combinations by cell area and notes capacity. [Undated grid reference](https://www.betacalendars.com/blank-calendar) · [project home](https://www.betacalendars.com/) ## Computed examples February 2027 is the compact four-row case; May 2027 requires six rows Monday-first; October 2027 is a representative five-row case. The month geometry is calculated here, independently of the printable references: [February](https://www.betacalendars.com/february-calendar.html) · [May](https://www.betacalendars.com/may-calendar.html) · [October](https://www.betacalendars.com/october-calendar.html).33:T1bd8,const app2 = (() => { const P={A4:[210,297],Letter:[215.9,279.4],A5:[148,210],Legal:[215.9,355.6]},M=["January","February","March","April","May","June","July","August","September","October","November","December"],W=["Sun","Mon","Tue","Wed","Thu","Fri","Sat"],root=document.createElement("section");root.style.cssText="font:14px/1.5 system-ui,sans-serif;color:#17233b;background:#fbfaf6;padding:22px;border:1px solid #dfe6e8;border-radius:14px;max-width:1050px;margin:auto"; const css=document.createElement("style");css.textContent=".s2ctrl{display:flex;gap:12px;flex-wrap:wrap}.s2ctrl label{display:grid;font-size:12px;gap:3px}.s2ctrl select,.s2ctrl input{padding:7px;border:1px solid #bac7cf;border-radius:7px;background:white}.s2grid{display:grid;grid-template-columns:repeat(7,1fr);gap:3px}.s2grid span{background:#edf3f3;padding:4px;text-align:center;font-size:11px}.s2card{background:white;border:1px solid #dce3e7;border-radius:10px;padding:14px;margin:12px 0}.s2small{color:#536174;font-size:13px}";root.append(css); const h=document.createElement("h2");h.textContent="Constraint solver";root.append(h);const bar=document.createElement("div");bar.className="s2ctrl";function select(label,values){const l=document.createElement("label");l.textContent=label;const s=document.createElement("select");values.forEach(x=>{const o=document.createElement("option");o.value=x;o.textContent=x;s.append(o)});l.append(s);bar.append(l);return s} const paper=select("Paper",Object.keys(P)),orient=select("Orientation",["Portrait","Landscape"]),month=select("Month",M),week=select("Week starts",W),rowsMode=select("Rows",["Natural","Fixed 42"]);function range(label,min,max,val,step){const l=document.createElement("label");l.textContent=label;const x=document.createElement("input");x.type="range";x.min=min;x.max=max;x.value=val;x.step=step;l.append(x);bar.append(l);return x} const margin=range("Margin · mm",5,30,12,1),titleH=range("Title · mm",8,35,18,1),headerH=range("Weekday header · mm",6,20,9,1),notesH=range("Notes · mm",0,70,28,2);root.append(bar);const result=document.createElement("div");result.className="s2card";root.append(result);const compare=document.createElement("div");compare.className="s2card";root.append(compare);const pareto=document.createElement("div");pareto.className="s2card";root.append(pareto); function leap(y){return y%4===0&&(y%100!==0||y%400===0)}function days(y,m){return[31,leap(y)?29:28,31,30,31,30,31,31,30,31,30,31][m-1]}function wd(y,m,d){return new Date(Date.UTC(y,m-1,d)).getUTCDay()}function off(y,m,w){return(wd(y,m,1)-w+7)%7}function nr(y,m,w){return Math.ceil((off(y,m,w)+days(y,m))/7)} function calc(name,ori,mar,tit,head,note,m,ws,fix){let [pw,ph]=P[name];if(ori==="Landscape")[pw,ph]=[ph,pw];const iw=pw-2*mar,ih=ph-2*mar-tit-head-note,r=fix?6:nr(2027,m,ws),gh=ih/r,cw=iw/7,area=cw*gh;return {pw,ph,iw,ih,r,gh,cw,area,valid:iw>0&&ih>0&&cw>=12&&gh>=12}} function draw(){let m=M.indexOf(month.value)+1,ws=W.indexOf(week.value),fix=rowsMode.value==="Fixed 42",q=calc(paper.value,orient.value,+margin.value,+titleH.value,+headerH.value,+notesH.value,m,ws,fix);result.replaceChildren();const hh=document.createElement("h3");hh.textContent=M[m-1]+" 2027 · "+paper.value+" "+orient.value.toLowerCase();result.append(hh);const p=document.createElement("p");p.className="s2small";p.textContent=q.valid?"Printable bounds: "+q.iw.toFixed(1)+" × "+q.ih.toFixed(1)+" mm · "+q.r+" rows · cell "+q.cw.toFixed(1)+" × "+q.gh.toFixed(1)+" mm · cell area "+q.area.toFixed(0)+" mm² · grid area "+(q.iw*q.ih).toFixed(0)+" mm²":"Invalid geometry: margins and reserved regions exceed the paper, or cells fall below the 12 mm minimum.";p.style.color=q.valid?"#36576b":"#a33";result.append(p); const svg=document.createElementNS("http://www.w3.org/2000/svg","svg");svg.setAttribute("viewBox","0 0 440 300");svg.setAttribute("role","img");svg.setAttribute("aria-label","Normalized paper layout preview");const ns="http://www.w3.org/2000/svg",sc=Math.min(360/q.pw,235/q.ph),x0=40,y0=25,pw=q.pw*sc,ph=q.ph*sc;function rect(x,y,w,h,fill,stroke){const e=document.createElementNS(ns,"rect");[["x",x],["y",y],["width",w],["height",h],["fill",fill],["stroke",stroke||"#728696"]].forEach(a=>e.setAttribute(a[0],a[1]));svg.append(e)}rect(x0,y0,pw,ph,"#fff","#263c52");const mx=+margin.value*sc,top=+titleH.value*sc,head=+headerH.value*sc,notes=+notesH.value*sc;rect(x0+mx,y0+mx,q.iw*sc,top,"#dfeeed");rect(x0+mx,y0+mx+top,q.iw*sc,head,"#b9d8d5");const gy=y0+mx+top+head,gh=q.ih*sc;for(let i=0;i<7;i++)for(let j=0;jLayoutCell area mm²Cell shapeStatus";const tb=document.createElement("tbody");[["A4","Portrait"],["Letter","Portrait"],["A4","Landscape"],["Letter","Landscape"]].forEach(([p,o])=>{const a=calc(p,o,+margin.value,+titleH.value,+headerH.value,+notesH.value,m,ws,fix),tr=document.createElement("tr");tr.innerHTML=""+p+" "+o+""+a.area.toFixed(0)+""+(a.cw/a.gh).toFixed(2)+":1"+(a.valid?"Feasible":"Invalid")+"";tb.append(tr)});table.append(tb);compare.append(table); pareto.replaceChildren();const phh=document.createElement("h3");phh.textContent="Margin–notes trade-off";pareto.append(phh);const candidates=[];for(let mar=6;mar<=24;mar+=3)for(let note=8;note<=56;note+=8){const a=calc(paper.value,orient.value,mar,+titleH.value,+headerH.value,note,m,ws,fix);if(a.valid)candidates.push({mar,note,area:a.area})}const front=candidates.filter(a=>!candidates.some(b=>b.area>=a.area&&b.note>=a.note&&(b.area>a.area||b.note>a.note)));const svg2=document.createElementNS(ns,"svg");svg2.setAttribute("viewBox","0 0 600 190");svg2.setAttribute("role","img");svg2.setAttribute("aria-label","Feasible Pareto trade-off between notes height and day cell area");candidates.forEach(a=>{const c=document.createElementNS(ns,"circle");c.setAttribute("cx",30+a.note*8);c.setAttribute("cy",170-a.area/20);c.setAttribute("r",front.includes(a)?5:3);c.setAttribute("fill",front.includes(a)?"#176f76":"#9cb9bf");svg2.append(c)});pareto.append(svg2);const pp=document.createElement("p");pp.className="s2small";pp.textContent="Each point is a feasible margin/notes candidate. Larger cells trade against larger notes regions; highlighted points are nondominated within this sampled grid, not a universal optimum.";pareto.append(pp) } [paper,orient,month,week,rowsMode,margin,titleH,headerH,notesH].forEach(x=>x.addEventListener("input",draw));[paper,orient,month,week,rowsMode].forEach(x=>x.addEventListener("change",draw));draw();return root; })(); app234:[] 30:{"id":"a91a738add58d600","slug":"printable-calendar-constraint-solver","title":"Printable Calendar Constraint Solver","thumbnail":"e6b271edab1c266814b013426b20c9928136892490ba276dc7b5256393261ba1","access_level":"public","create_time":"$D2026-10-07T11:20:55.099Z","update_time":"$D2026-10-07T11:28:53.174Z","view_time":null,"first_public_time":"$D2026-10-07T11:38:19.354Z","has_unpublished_edits":null,"fork":false,"stars":0,"starred":false,"owner":{"type":"team","id":"0608cb6e6fdd19ad","login":"mateopedersen","name":"Mateo Pedersen","avatar_url":"https://avatars-next.observableusercontent.com/1656f6350cbcad592ca7fe8675140cd56effd725832498d28117b54dc11cfe4b","tier":"free_2026","bio":"Independent product builder exploring calendar computation, printable-layout geometry and temporal data visualization. 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